Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. Once a wellbore is drilled, a casing is then lowered and set in place.
In many wells, it can be difficult to run the casing to great depths because friction between the casing and the wellbore during run-in often results in a substantial amount of drag. This is particularly true in horizontal and/or deviated wells, where, in some cases, the drag on the casing can exceed the available weight of the casing in the vertical section of the wellbore that would otherwise tend to progress the casing further along. If there is insufficient weight in the vertical portion of the wellbore, it can be difficult or impossible to overcome the drag in the wellbore, thus limiting the depth to which the casing can be run or preventing completion of a horizontal or deviated well.